como se dice "you"?
I'm really confused. I searched on the translation here for how to say "you", and the informal version is "tú", which I knew, but sometimes people say "su" instead of "tu" and I searched that and it came up with "his"??!! Please help! 
3 Answers
There are two kinds of "you": tú - informal and usted - formal, used when talking to someone in authority.
There are four, if you include the plural (and "you" in English is ambiguous): "tú", "usted", "vosotros", "ustedes".
"su" is not a subject pronoun at all but, rather, a possessive pronoun/adjective and, thus, is "your" in English.
su is used as a possessive. It means 'your', in the Ud. form, and it can also mean 'his' or 'hers'
There are two kinds of "you": tú - informal and usted - formal, used when talking to someone in authority.
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